Hydrofluorocarbon (HFC) products are widely utilized in many applications, including refrigeration, air conditioning, foam expansion, and as propellants for aerosol products including medical aerosol devices. Although HFC's have proven to be more climate friendly than the chlorofluorocarbon and hydrochlorofluorocarbon products that they replaced, it has now been discovered that they exhibit an appreciable global warming potential (GWP).
The search for more acceptable alternatives to current fluorocarbon products has led to the emergence of hydrofluoroolefin (HFO) products. Relative to their predecessors, HFOs are expected to exert less impact on the atmosphere in the form of a lesser or no detrimental impact on the ozone layer and their much lower GWP as compared to HFC's. Advantageously, HFO's also exhibit low flammability and low toxicity.
As the environmental, and thus, economic importance of HFO's has developed, so has the demand for precursors utilized in their production. Many desirable HFO compounds, e.g., such as 2,3,3,3-tetrafluoroprop-1-ene or 1,3,3,3-tetrafluoroprop-1-ene, may typically be produced utilizing feedstocks of chlorocarbons or chlorofluorocarbons, and in particular, chlorinated propenes.
Unfortunately, many chlorinated propenes may have limited commercial availability, and/or may only be available at potentially prohibitively high cost, due at least in part to the propensity of the conventional processes typically utilized in their manufacture to result in the production of large quantities of waste and/or by-products. For example, many conventional processes for the production of chlorinated propenes require only partial conversion of the limiting reagents, so that excessive conversion of the same results in the production of large quantities of by-products. Excess waste may be produced in trying to limit conversion to the desired level by quenching the reaction with water, or other aqueous solvents, since use of the same in a chlorination process can result in the production of large quantities of aqueous HCl that is of lower value than anhydrous HCl. Quenching such reactions with nonaqueous solvents can also be suboptimal, since any amount of backmixing or increased residence time of unconverted limiting reagents, no matter in what solvent, can lead to undesirable conversion levels, and a reduction in reaction selectivity.
Any such waste and/or by-products produced not only have to be separated from the final product and disposed of, but also, can result in system fouling prior to doing so. Both of these outcomes can introduce substantial expense, further limiting the commercial potential of processes in which the production of such waste and/or by-products is not reduced or eliminated. Further, these problems become exacerbated on process scale-up, so that large scale processes can become cost prohibitive quickly.
Quench mechanisms utilizing nonaqueous solvents have been proposed, but have been proposed for use in connection with quench designs that are inappropriate for use in many processes for the production of chlorinated propenes. That is, conventional weir or spray quench designs may typically result in an amount of backmixing occurring that, while acceptable within the context in which these quench designs are used, is unacceptable in processes in which high conversion rates can result in the formation of unacceptable amounts of by-products. Also, in order to provide the amount of cooling desired, conventional quench mechanisms capable of utilizing organic cooling fluids are typically designed to accommodate a very high flow rate of process and/or quench fluid.
It would thus be desirable to provide improved processes for the production of chlorocarbon precursors useful in the synthesis of HFO's. More particularly, reduction in the amount of waste and/or by-products that are produced, without undesirable increases in conversion rates or decreases in reaction selectivity, or improved methods of cost-effectively managing any by-products and/or waste products that are produced, would provide significant commercial advantage.